A conventional pneumatic stapler employs powerful pneumatic machine to eject a staple to penetrate an object. In order to ensure a safety operation when using the pneumatic stapler, a safety plate is equipped in each of the conventional pneumatic staplers so that then trigger can only be pulled when the safety plate is unlocked. However, there is a dangerous situation that the pneumatic stapler could be unintentionally triggered to hurt people, that is when the magazine is removed from the barrel of the pneumatic stapler. This happens when the staples are jammed in the barrel and the user wants to withdraw the shooting problem so that he/she removes the magazine from the barrel and checks or removes the jammed staples. During the checking or removal of the jammed staples, the trigger could be pulled unintentionally and a staple ejects out from the barrel and hurts people.
The present invention intends to provide a safety device that is rotated when the magazine is removed and stops the safety plate from moving so as to avoid the trigger from being pulled.